Self-propelled thresher



FIG. 1 is a front elevational view of a self-propelled thresher showing our new design;

FIG. 2 is a right-side elevational view thereof;

FIG. 3 is a left-side elevational view thereof;

FIG. 4 is a rear elevational view thereof; and

FIG. 5 is a top plan view thereof. 

The ornamental design for a self-propelled thresher, as shown and described. 